Spark-plug.



L. A. MCDOWELL.

SPARK PLUG.

APPLICATION FILED APR. I6. 1917.

Patented Nov. 27, 1912.

LEWIS A. EoDOWELL, F LUV'EBNE, MINNESOTA.

eraan-PLUG.

To all whom it may concern:

Be it known .that I, Lnwis A.4 McDownLL, a citizen of the United States, and a-resident of Luverne, in thecounty of Rock and State of Minnesota, have invented certain new and useful Im rovements in Spark-Plugs, of

which the ollowing is a specification.

VThe present invention relates to ignitionV means for internal combustion engines.

The spark plug presented in my S. Patent #1,196,566, August 29, 1916, includes a split collar threaded into the body of the plug' and provided with a depending U- sha ed member carrying the lower electrode. This collar is provided to afford means for varying the relation of the electrodes as stated 1n the patent, but it has been found that the device suffered from the fact that the collar `failed to remain fixed after being adjusted due to the fact that the vibration of the engine tends to cause the collar to unturn from the plug and 4thereby increase the space between the electrodes.

The present invention has, therefore, for its primary object the provision in a `spark'. plug of this type of means for preventing Theinvention is a distinct improvement several views, of which,-

Fig. 2 is a o'vertlie device disclosed in my patent above mentioned, inasmuch as the electrode carrying collar can be freely screwed linto the, body yet can be unscrewed only by application of a wrench and cannot be displaced by vibration'of the motor.

The invention willbe clearly understood Bpccillcation of'Letters Patent. .p'plleatlnn led April 16, 1917. Seriallo. 162,260.

Plg

ig.. 5 is an elevation of the insulating co Patented Nov. 27, 191 v.

Referring, now, to the illustrations, the plugv illustrated includes a shell, -5, threaded on its lower end as at 6, adapting 'it .tobe readily The s ell, 5, has a bore, 7, extending therethrough which bore is threaded at its lower end as alt 8, to receive an externally-threaded collar, 9, having a depending U-shaped member 10, carrying in its'web an upwardly extendingl electrode, 11. The collar is split longitud1nally,.as at 12, adjacent one of the arms of the member, 10, affording a relatively large segmcntal portion, 13, which is free to expand and engage, at its edge, 14,'

the shell to prevent unturning of the collar.

screwed into the cylinder as usual.

Obviously, with the slot, 12 positioned as illustrated, the collar is right threaded but if it were left threaded the slot would necessarilybe adjacent .the opposite arm ofthe member, 10.

It is evident that this arran ement permits the collar to be screwed readily into` the shell but experience and many tests have proven that the vibration does'not tend to screwthe collanu wardly but will screw lit downwardly un ess means are provided di'erent from the construction disclosed in my prior patent.

16, is the insulating core inclcsed by the shell and held therein by a gland nut, 17, threaded into the body. 18, is the center electrode which is'carried by the insulator, 16, and supported thereby in spaced relation to the lower electrode.

Having thus described my invention what I claim as new and desire to secure by Letters Patent of the United VStates In a spark-plug a shell internally-threaded at its lower en an upper electrode, and a collar threaded into4 the shell and provided with a U-shaped depending member carrying an electrode to coact the upper electrode, the collar being of yieldable material and split adjacent one of the arms of said member, the free edge of the collar being engageable -with the shell to prevent unscrewing of the collar.

In testimon whereof, I have hereunto set my hand t is 5th day of April, 1917.V 

